"Nicole is just so heartbroken and completely devastated," a source said at the time. But the X Factor judge didn't let any signs of sadness show as she posed for photos at her backstage birthday party tea. The singer, whose actual birthday was on 29 June, laughed and smiled as she blew out the candles on her giant chocolate cake.

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Friends and colleagues had rallied around the birthday girl to make her celebration as memorable as possible. The party place was decked out with fuschia, black and white balloons.

Humorous gifts for Nicole included an English-Welsh dictionary – a nod to the place where they were filming.

Nicole and Lewis split after five years together. The news broke on Monday and surprised fans who had believed that Lewis was going to propose. "We've been together for five years, which is quite a milestone really," Lewis revealed recently.

"But hopefully in the near future," he added when quizzed about popping the question. "Maybe before we get to six years."

They are believed to have ended their relationship because of their busy work schedules and the fact that they reside in different countries.

The couple went public with their romance back in 2007 after meeting at the MTV Music Awards.

The pair, who celebrated their five year anniversary just a month ago on the beautiful island of Capri, were last pictured together at the Canadian Grand Prix in Montreal on 10 June.

Since then, Nicole has gone solo at various events. She headed to Wimbledon last week and gave a stunning performance at the Summer Music Festival in Rome, Italy.

The couple had already split briefly in 2011, as well in 2010. Nicole, 35, is based in the US and has been busy back in her judge's seat on X Factor while Lewis, whose base is in Switzerland, has been taking part in F1 races around the world.

A source told The Sun: "It's so hard to keep up a relationship when they’re barely in the same country as each other.

"Both have supported each other in their careers and will continue to do so. But the nature of their work ultimately cost their relationship."